Every cold email program needs domain warmup. But warmup tools vary significantly on seed network size, warmup speed, and how honestly they present what they can and cannot fix. This guide compares the top 5 email warmup tools with real numbers - plus the one thing no warmup tool can fix.
| Tool | Price/inbox/mo | Seed Network | Warmup Speed | Best For |
|---|---|---|---|---|
| Instantly Warmup | Free (with Instantly plan) | Included 5K-50K inboxes | Fast - 6-8% daily ramp | Teams already using Instantly for sending |
| Lemwarm (Lemlist) | $29/mo standalone | 8,000+ inboxes | Moderate - 5-7% daily ramp | Teams using Lemlist or who want domain health monitoring |
| Mailreach | $25/mo | From real G Suite users | Moderate-fast | Teams that want best-in-class deliverability testing alongside warmup |
| Warmbox | $19/mo | 35,000+ inboxes | Fast - multiple templates | Budget-conscious teams; good ROI at this price point |
| Allegrow | $20-40/mo | From real company inboxes | Slow but high-quality | Teams that prioritise network authenticity over speed |
A fresh domain with no sending history will be treated with suspicion by Gmail, Outlook, and Yahoo. Warmup builds a base reputation that makes inbox placement possible.
If you stopped sending for 60+ days, your domain reputation can decay. Warmup restores it before restarting campaigns.
If you experienced one bad campaign, warmup helps rebuild the positive engagement signal over 4-6 weeks.
If you send to an unverified list with 5%+ bounces, warmup cannot fix the damage faster than the real campaigns are causing it. Verify the list first.
If your domain or IP is on a Spamhaus or Microsoft blocklist, warmup tools have no mechanism to remove you from that list. Contact the blacklist operator directly.
If your emails contain spam trigger words or are flagged for content reasons, warmup does not change how the content is scored. Fix the copy.
| Week | Daily warmup volume | Campaign sends allowed? | What’s happening |
|---|---|---|---|
| Week 1-2 | 10-25/day | No | Domain is being introduced to Gmail, Outlook, Yahoo. Building a history. No real sending yet - any spam complaints at this stage could permanently damage reputation. |
| Week 3-4 | 25-50/day | Not yet (low volume only) | Reputation is building. You may start with very low-volume campaigns (10-15 emails/day to highly targeted, verified contacts). |
| Week 5-6 | 50-100/day | Yes - with verified list only | Domain has sufficient reputation history. Campaigns should go to a 100% verified list only. Continue warmup in parallel. |
| Week 7-8+ | 100-200/day | Yes - full campaign volume | Domain is campaign-ready. Keep warmup running at 50-100/day in parallel to maintain reputation signal. Never turn warmup off entirely. |
A warmed domain sent to a dirty list loses its reputation in days. Always verify your list before every campaign. 100 free credits, no card required.
Provider behaviour, DNS setup, warm-up, and inbox placement
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